The present disclosure generally relates to methods and compositions comprising cinnamaldehyde and zinc. More specifically, the present disclosure relates to administering an amount of cinnamaldehyde that is suitable for oral consumption and, in combination with zinc, increases energy expenditure and fat oxidation and/or improves one or more of insulin sensitivity, glucose tolerance, mood, memory or cognition.
During the past decades, the prevalence of obesity has increased worldwide to epidemic proportion. Approximately 1 billion of people worldwide are overweight or obese, conditions that increase mortality, mobility and economical costs. Obesity develops when energy intake is greater than energy expenditure, the excess energy being stored mainly as fat in adipose tissue. Body weight loss and prevention of weight gain can be achieved by reducing energy intake or bioavailability, increasing energy expenditure, and/or reducing storage as fat.
Research on the molecular mechanisms underlying pungent sensations revealed the existence of two cation channels, TRPV1 (transient receptor potential V1) and TRPA1 (transient receptor potential A1) that are expressed in the somatosensory fibers innervating the oral cavity. TRPV1 is the receptor for heat and burning sensations such as capsaicin, the spicy compound of chili peppers. TRPA1 responds to cold and pungent compounds; at moderate concentrations, TRPA1 agonists exhibit a pleasant tingling sensation.
The TRPV1 agonist capsaicin is well known as increasing energy expenditure and fat oxidation, but the efficient doses are intermediate to high (20 mg and more). See, e.g., Ludy et al, “The effects of hedonically acceptable red pepper doses on thermogenesis and appetite,” Physiol. Behav., Mar. 1, 102(3-4): 251-8 (2011). Moreover, capsaicin is a particularly pungent and toxic compound. Physiological effects associated with oral administration of capsaicin include a burning sensation of heat from the mid-tongue to the throat, shortness of breath, fainting, nausea, and spontaneous vomiting. As a result, only small quantities of capsaicin may be administered without causing discomfort to the individual. Food products containing capsaicin are frequently not accepted by the consumer because such products provide a very unpleasant mouth feeling. In particular, the burning effects are considered to be very unsavory, affecting the consumption of the food product.
So far, the only spice-derived ingredient showing an impact on human metabolism is capsaicin. For example, a study that investigated the effect of mustard, horseradish, black pepper and ginger on energy balance and food intake in humans did not identify any effect of these raw spices. Gregersen et al., “Acute effects of mustard, horseradish, black pepper and ginger on energy expenditure, appetite, ad libitum energy intake and energy balance in human subjects,” Br. J. Nutr., 5:1-8 (July 2012). However, the effective dosage of capsaicin is too intense to be included in a food product, due to spicy taste, or to be ingested, due to gastrointestinal intolerance.
The cinnamon-derived compound cinnamaldehyde is α,β-unsaturated aldehyde that activates TRPA1, but not TRPV1 or TRPM8, with an EC50 of approximately 10 μM. Cinnamaldehyde interacts with TRPA1 in a covalent manner. Cinnamaldehyde has a flavor that is less intense than capsaicin. Nevertheless, cinnamaldehyde is pungent at relatively high concentrations and has a strong cinnamon flavor.
Another condition adversely affecting some individuals is that their body tissues do not respond properly to insulin. Insulin receptors in the tissues cease to function adequately, and gluco-dependent cells fail to recognize the presence of insulin. As a result, the pancreas needs to secrete more insulin to help glucose enter these cells. The pancreas tries to keep up with this increased demand for insulin by producing more. This phenomenon is called insulin resistance (also known as low insulin sensitivity). Many people with insulin resistance have high levels of both glucose and insulin circulating in their blood at the same time. Eventually, the pancreas fails to keep up with the body's need for insulin, leading to Type II diabetes.
Insulin resistance and Type II diabetes are associated with increased risk of heart attacks, strokes, amputation, diabetic retinopathy, and kidney failure. For extreme cases, circulation of limbs is affected, potentially requiring amputation. Loss of hearing, eyesight, and cognitive ability has also been linked to these conditions
Management of insulin resistance in children and adults is essentially based on dietary and lifestyle changes, including healthier dietary habits and increased exercise. These practices can be very efficient in improving insulin sensitivity and in slowing the progression of the disease, but they are difficult to apply and actually not followed by most patients. Type II diabetes can be treated with drugs promoting insulin sensitivity, but their efficacy in reducing the rate of progression of the disease is quite low. Insulin treatment is required during the most advanced phases of the disease.
Products containing n-3 polyunsaturated fatty acids, fibers, oligosaccharides and even probiotics have been proposed as nutritional solutions to improve insulin sensitivity and to reduce insulin resistance. However, the efficacy of these nutritional interventions is quite marginal and even controversial, with studies showing no or even deleterious effects.
The TRPV1 agonist capsaicin can improve insulin sensitivity; however, as noted above, capsaicin is a particularly pungent and toxic compound, and the effective dosage of capsaicin is too intense to be included in a food product, due to spicy taste, or to be ingested, due to gastrointestinal intolerance.
Yet another condition adversely affecting some individuals is impaired neurotransmission, for example low levels of neurotransmitters such as epinephrine. Impaired neurotransmission is connected to mood disorders such as depression, anxiety disorders, and increased susceptibility to stress, and also connected to cognitive dysfunction.
Carbohydrate-rich foods are known for providing important metabolic fuel for physical performance, but their effects on mood and cognitive performance are not very clear. However, irritability and aggression are influenced by individual differences in insulin release, the frequency that meals are eaten, and the effect of these meals on blood glucose values. Benton, “Carbohydrate ingestion, blood glucose and mood,” Neuroscience and Biobehavioral Reviews, 26:293-308 (2002). Furthermore, the ability to control the levels of blood glucose is related to both mood and cognition. For example, in a study in which participants were given an oral glucose tolerance test and cognitive tests, the older age group showed that those with poorer glucose tolerance forgot more words and had slower decision times; and, in those participants with poor glucose tolerance, a tendency for blood glucose to fall below baseline values was associated with better mood and faster working memory. Young and Benton, “The nature of the control of blood glucose in those with poorer glucose tolerance influences mood and cognition,” Metab. Brain Dis. (Mar. 26, 2014).